Control system for an electrified fence

ABSTRACT

An automatic as well as manually operated switching system for selectively applying relatively high voltage pulses to an electrified fence from one of a pair of fence charger units commonly referred to as &#39;&#39;&#39;&#39;fencers.&#39;&#39;&#39;&#39; In its automatic mode, an interface switching circuit under the control of a monitoring circuit senses the condition of the high voltage applied to a fence circuit from a first fencer unit and in the event of the occurrence of a predetermined abnormal operating condition, causes a switchover to a second fencer unit which, after a predetermined manually adjustable delay to allow for a varying number of shocks, is caused to turn on and apply its respective high voltage pulses to the fence circuit. The monitor circuit in one embodiment is also adapted to operate as a portable metering unit for trouble shooting the fence circuit.

United States Patent 1191 Finch et al.

[111 3,873,847 Mar. 25, 1975 CONTROL SYSTEM FOR AN ELECTRIFIED PrimaryExaminer-Robert K. Schaffer FENCE Assistant ExaminerM. Ginsburg [76]Inventors: John H. Finch, P O BOX 112, 102 Attorney, Agent, or F1rm-B.P. F1shburne, Jr.

McDonald St.; Marion A. Everett, 5 ABSTRACT Sycamore St., PO. Box 83,both of Pave 31778 An automat1c as well as manually operated switchmgsystem for selectively applying relatively high voltage Flledi 1974pulses to an electrified fence from one of a pair of [21] APP].102443353 fence charger units commonly referred to asffencers. In 1tsautomatic mode, an interface switching circuit under the control of amonitoring circuit senses [5 Cl 307/132 276/ the condition of the highvoltage applied to a fence [5!] Int. Cl. HOZj 9/00 circuit from a firstfencer unit and in the event of the Fleld of Search 307/132 132occurrence of a predetermined abnormal operating 307/132 EA. 132 M. 64condition, causes a switchover to a second fencer unit which, after apredetermined manually adjustable I References Clted delay to allow fora varying number of shocks, is UNITED STATES PATENTS caused to turn onand apply its respective high voltage 3 409 7 3 11 19 Baehr et a].IIIIIIIIIIIIIIIIIIIIIII H pulses to the fence circuit. The monitorcircuit in one 3,772,529 11/1973 Boeing 307/132 R embodiment is alsoadapted to Operate as a Portable metering unit for trouble shooting thefence circuit.

Claims, 7 Drawing Figures HIGH VOLTAGE MONITOR PLUG IN 2 H. V. METERH.V. SENSING MODULE L64 tea has he? lealespto 4 O: M. LINE 52 53 VOLT 20nfkZl 4 150 INTERFACE H'GH ILC. LINE VOLT) C AG LINE VOLT H'GH ONTROLLERVOLTAGE FOR jg VOLTAGE 56 FENCER FENCER HIGH VOLT H|GH VOLTAGE HIGH VOLTO 2 EN E i- 15 F c R 15 J SWITGHI NG /72 HIGH VOLTAGE 0130011111301 7WARNING t 29 SWITCHES DEVICE 28 Q g fi L J H 75 I5 0 mm 60 E VOLTAGECONTROL SYSTEM FOR AN ELECTRIFIED FENCE BACKGROUND OF THE INVENTION Thisinvention relates generally to high voltage electrified fence apparatusand more particularly to a system for switching the high voltage appliedto an electrifled fence from one fencer unit to another in the event ofany departure from a predetermined set of operating conditions.

Fence chargers or fencers as they are commonly referred to, are wellknown to those skilled in the art. Such apparatus generates a relativelyhigh voltage, low current signal which is applied to an electricalconductor encircling a predetermined perimeter for repelling livestock,for example, coming in contact with the conductor and thus preventingbreakout from an enclosed area. The fence circuit conductor is insulatedfrom ground i.e. open circuited such that any subject having contactwith the ground and coming in contact with the conductor completes theground return for the fencer and in the process receives a shock. Ingenereal two major types of fencer output signals are utilized, a pulsetype signal or a sine wave type signal. The pulse type signal isnormally of a relatively higher voltage (typically 12,000 volts) whilethe sine wave type signal is of a larger duration and lower in voltage,being in the order of 6,000 volts. A repetition rate of one shockingcycle every 1.5 5,0 or more seconds for an unloaded fence moreover isobtainable depending on the make and/or model of the fencer utilized.

Typical examples of such apparatus are disclosed in the following U.S.Pat. Nos. 2,429,764, Moore; 2,801,350, Saunders; 3,115,610, Beguin;3,182,211, Maratuech; 3,378,694, Griffeth; 3,384,788, Johnston;3,655,994, Malme; and 3,655,995, Malme. Such apparatus is notnecessarily limited to such a use, however, when desirable it may beutilized for the prevention of the intrusion into a predetermined area.

While electrical systems are also known which include back-up orstand-by power systems with automatic switching to prevent power outagesin emergency, these sytems are for more general utility and do notrelate particularly to or are adapted for electric fence apparatus.Examples of these types of systems are disclosed in the following U.S.Pat. Nos. 3,041,465, Ayre; 3,596,106, Raddi', 3,201,592, Runert; and3,646,355. Ireland.

SUMMARY Briefly, the subject invention is directed to control circuitryfor electric fence apparatus and comprises an interface controll underthe influence and control of a voltage monitoring circuit which sensesthe high voltage signal applied to an electrified fence from a selectiveone of two fencer units. The high voltage is applied to the fencethrough the controller circuitry such that whenever a departure fromnormal operating conditions occurs, the monitoring circuit senses thecondition and causes the controller to automatically switch to the otherfencer unit which has remained until now in a deenergized standby state.In the event of a malfunction, the interface controller provides anindication that a malfunction has occurred and a switchover to the otherfenser unit has been made. The monitoring circuit comprises twoembodiments, one of which is adapted to operate as an ungroundedportable metering unit for remote operation whereby testing of the fencemay be made for detecting shorts, open circuits and the like and whendesirable, without actual contact with the fence thus permitting safe,relatively easy trouble shooting and repair, particularly during badweather conditions. The second embodiment consists of a substitutecircuit for the first embodiment when in remote operation.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view physicallyillustrating the com bination of the interface controller unitcontemplated by the subject invention and two embodiments of voltagemonitors associated therewith;

FIG. 2 is an electrical block diagram illustrative of the systemcontemplated by the subject invention;

FIG. 3 is an electrical schematic diagram of the preferred embodiment ofthe interface controller circuitry;

FIG. 4 is an electrical schematic diagram of the preferred embodiment ofthe first type of monitor circuit shown in FIG. 1;

FIG. 5 is an electrical schematic diagram illustrative of the secondtype of monitor circuit shown in FIG. 1;

FIG. 6 is a perspective view of fence disconnect means associated withthe subject invention; and

FIG. 7 is a vertical cross sectional view of the disconnect means shownin FIG. 6.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the figures,and more particularly to FIG. 1, reference numeral 12 designates ahousing or junction box which is adapted to contain interface controllercircuitry for providing either manual or automatic switching from aprimary high voltage fencer, not shown, to a second or back-up fencer,also not shown. The interface controller circuitry included in thehousing 12 is shown by reference numeral 13 in the block diagram at FIG.2 and the schematic appearing at FIG. 3. The housing 12 shown in FIG.includes a pair of high voltage leads l4 and 16 which are respectivelyadapted to be coupled to the high voltage output from the pair of fencerunits. The housing 12 includes a body cavity 18 having a multiple pinfemale connector 20 and a single pin female connector 21. Connector 20makes connection both to the first embodiment of a monitor unit which isshown by reference numeral 22 as well as the second embodiment thereofwhich is shown by reference numeral 24. Female connector 21 on the otherhand only makes connection to monitor circuit 24 for coupling the fencerhigh voltage thereto when utilized. A pair of output terminals 26 and 28are located on one side wall portion 26 of the housing 12. Terminal 26comprises the high voltage output terminal and is adapted to beconnected to the fence perimeter wire conductor 29 shown in FIG. 2 whileterminal 28 is connected to earth ground.

The front panel 27 of the housing 12 contains four fuse holders 30, 32,34 and 36, which are adapted to contain respective fuse pairs for twoseparate AC line voltage circuits and respective returns therefor. BothAC line circuits are adapted to be coupled to a common AC power sourcethrough an AC line cord 38. A manual reset switch 40 comprising a doublepole three position switch, to be referred to later. is also mounted onthe front panel 27 of the housing 12 as well as three indicator lamps42, 44 and 46. Also a sensitivity control 48 is mounted on the frontpanel 27. The indicator lamps are adapted to provide a visual indicationof the system operation while the control 48 is adapted to provide amanual sensitivity setting for controlling the operating point at whichsystem switchover from one high voltage fencer to another is to occur.

The first embodiment of the monitor circuit shown by reference numeral22 in FIG. 1 as noted earlier is adapted to be utilized as a hand heldtest instrument for trouble shooting the fence circuit 29 (FIG. 2). Thisis accomplished by unplugging the monitor circuit 22 from the plug-inreceptacle in the housing 12 and coupling a high voltage probe includingan insulating body member 50, a metal tip 51, and female connectormember 20' identical to connector 20 coupled to the male connector 52.When the high voltage probe is connected to the test unit 22, the metaltip 51 is adapted to contact the fence circuit for normal meteringoperation; however, for quick checks and/or during bad weather it isadapted to act as a radio antenna to provide capacitive and inductivepick up from the high voltage fence 29, thus permitting operation and setion whereupon the remainder of the line is energized. By moving fromone disconnect to another the absence of fence high voltage (or shorts)can be found quickly and easily.

Automatic switching from the primary fencer unit 54 to the back-up unit56 is provided by the interface controller circuitry 13 in response tothe monitoring of the high voltage signals applied to the conductor 29by means of either the metering circuit 22 or the sensing module 24. Themetering circuit 22 is adapted to receive a volt DC supply potentialfrom the interface controller circuitry 13 on lead 63. This lead may forexample go to the male connector plug 52 coupled to the female connector20. The circuit operates in response to the high voltage applied to theconductor 29 which is sensed by means of a transformer 61 (FIG. 3) whosesecondary winding is coupled across leads through connector elements 20and 52. Each high voltage pulse or sine wave shock excites the secondarywinding of transformer 61 which generates a damped oscillation signalwhich in turn is coupled back to the interface controller circuitry oncircuit lead 66. This connection is also lected relative measurements tobe made several feet from the fence. The distance will vary depending onthe type of fencer unit used. When the testing unit 22 is being utilizedas a remote test instrument. the second embodiment in the monitorcircuit shown by reference numeral 24 is normally substituted in itsplace via the male plugs 53 and 55 being inserted into the femalemembers 20 and 21, respectively. The latter unit while being of adifferent circuit configuration. is still adapted to provide amonitoring function of the high voltage output to the fence and signal adeparture from a predetermined operating condition to the interfacecontroller circuitry for switching from a primary high voltage fencerunit to a back-up unit.

The system block diagram of the subject invention is shown in FIG. 2.Referring now to FIG. 2, reference numeral 54 refers to afirst orprimary high voltage fencer unit while reference unit 56 refers to asecond or backup high voltage fencer unit. Such apparatus is well knownand can be of any conventional design. A typical example particularlyadapted for use in connection with the subject invention ,is the modelSuper 98 solid state fencer unit manufactured by the InternationalElectric Company. The fencer units 54 and 56 receive selectivelyswitched AC power from the interface control circuitry 13 in the housing12 which as noted above receives AC input line voltage by means of theline cord 38. When selectively energized through the interfacecontroller circuitry 13, the fencer units 54 and 56 are adapted tosupply an individual high voltage output in the form of periodicallyoccurring pulse or sine wave modulated pulse signals varying in width,amplitude and frequency on respective high voltage conductors 14 and 16which feed into the interface control circuitry. The output terminals 26and 28 on the housing 12 are respectively adapted to be connected to thefence circuit 29 and earth ground 15. Both fencer units 54 and 56additionally have ground connections to earth ground 15. The fencecircuit 29 comprises a wire conductor mounted on insulators attached tosupporting stakes or poles. The wireis thus above the ground andelectrically isolated therefrom (open circuited). A plurality ofdisconnect switches 60 are adapted to be selectively connected in seriesalong the wire conductor 29 for interrupting the line at predeterminedlocamade through connector elements 52 and 20.

When the second or substitute module 24 is utilized in place of theremoved metering circuit 22, it is adapted to be coupled to the highvoltage output terminal 26 by means of circuit lead 67 which connects tothe single pin connector elements 55 and 21. An earth ground and a 30volt DC supply potential is applied by means of circuit leads 68 and 69which leads go through connector elements 53 and 20. The sensing module24 operates to couple a DC signal back to the interface controllercircuitry on circuit lead 70. Additionally, an external malfunctionwarning device 72 is adapted to be powered from the interface controllercircuitry 13 by means of an AC line pair 74 and 75.

Referringto the details of the interface controller circuitry 13 asschematically disclosed in FIG. 3, the input AC power applied by meansof line cord 38 shown in H6. 1 is coupled to pair of terminals 76 and 78with terminal 76 defining the hot side of the line, while terminal 78 isadapted to represent the return side of the line. From terminal 76, afirst and second AC line 80 and 82, respectively couple to movableswitch contact terminals 84 and 86 of the manually operable two-pole,three-position switch 40. This switch when desirable could be simply atwopole, two-position switch since the middle position 2 of switch 40 isfor convenience an open circuit position. The AC lines 80 and 82 arerespectively fused by means of the fuses 90 and 92 which are adapted tobe contained for example in fuse holders 30 and 34 shown in FIG. 1. Inaddition to being coupled to terminal 84, AC line 80 is also coupled tothe movable relay contact 94 of a solenoid operated relay 96 which isadapted to act as the switching device coupling the high voltage outputof either the first fencer unit 54 or the second fencer unit 56 tooutput terminal 26. More particularaly, high voltage signal leads 14 and16 from the fencer units 54 and 56 are coupled to respective fixed relaycontacts 98 and 100 of the contact set including the movabale contact102. Contact 102 is directly connected to high voltage output terminal26. Relay 96 additionally includes two other sets of relay contactsoperable in response to the energization of the solenoid 104 which hasone side coupled to the AC line 80 by the closure of switch contacts 84and 106. The other side is connected to AC line return 108 which iscoupled back to line terminal 78 through a second fuse 110 contained forexample in fuse holder 32. Relay 96 and the contacts associatedtherewith are,shown in a position at the time the solenoid 104 isdeenergized.

When switch contacts 84 and 106 of the manually operated switch 40 areclosed, i.e. position 1, the solenoid 104 is energized by theapplication of AC line voltage thereacross, whereupon indicator light 42on the front panel of the housing 12 goes on. AC line voltage is alsoapplied to the primary fencer unit 54 by means of circuit leads 114 and116 causing its high voltage fencer output to be provided on highvoltage lead 14 which due to the closure of relay contacts 98 and 102 byenergization of the solenoid 104 is coupled to fence conductor outputterminal 26. The indicator lamp 44 on front panel of the housing 12 isalso turned on to provide an indication that the fencer unit 54 isreceiving AC power and is coupled to the fence conductor 29. As long asthe manually operated switch 40 is in position 1, the primary fencerunit 54 will be the only unit capable of being applied to the fenceconductor 29.

In order to provide a manual or automatic switchover to the back-up orsecondary fencer unit 56, the second set of switch contacts includingcontacts 86, 120 and 122 of the manually operated switch 40 come intoplay. For manual operation only, it is to be noted that switch contacts120 and 122 are commonly connected to the primary winding of a powertransformer 124 as well as the movable relay contact 126 of relay 96.With switch 40 in position 1, switch contacts 86 and 120 are alsoclosed. The solenoid 104 being energized opens the circuit between relaycontacts 126 and 128. However, when switch 40 is moved to position 3,switch contacts 86 and 122 close. whereupon solenoid 104 is deenergizedand the circuit relay contacts 126 and 128 now closes. This applies ACline voltage to the other fencer unit 56 by means of AC line 130 with anAC return line 132 being provided back to AC line return terminal 78through fuse 134 which is contained in fuse holder 36. The fencer unit56 now receiving AC line voltlage generates its own high voltage outputsignal which appears on high voltage lead 16. Since lead 16 is coupledto relay contact 100 which due to the fact that solenoid 104 isunenergized, is now coupled to the high voltage output terminal 26 viathe movable relay contact 102. When the fencer unit 56 receives linevoltage indicator light 46 coupled across AC lines 130 and 132 also goeson noting that fencer unit 56 is now operating in place of fencer unit54.

In order to provide automatic switching from the primary fencer unit 54to the secondary or back-up fencer unit 56in the eventof for example aloss of output from the fencer unit 54, a holding relay 136 controlledby either the metering unit 22 or the module 24 is adapted to maintainrelay solenoid 104 of relay 96 energized when the manually operatedswitch 40 is moved from the position 1 to position 3 wherein switchcontacts 84 and 106 are open but where the other switch contacts 86 and122 are closed. The relay coil 138 for the holding relay 136 is coupledinto the output of voltage amplitude sensitive means such as a Schmitttrigger circuit 140 comprised of field effect transistor (FET) 142 andjunction transistor 144. The holding relay 136 additionally includes apair of normally open relay contact terminals 146 and 148. The holdingrelay is adapted to operate such that when the relay coil 138 isenergized duringnormal operation, the relay contact terminals 146 and148 are closed. It is to be noted further that relay contact terminal148 is connected to relay contact 150 of the high voltage switchingrelay 96 by means of circuit lead 152. Relay terminal 150 is adapted tobe closed with movable contact 94 when solenoid 104 is initiallyenergized by movement of the switch 40 to position 1. It can be seenthat ifthe holding relay 136 is also energized, the solenoid 104 will beheld energized from AC line back to line return 108 through the relaycontacts terminals 94 and 150 and 148 and 146 and circuit lead 154.

The Schmitt trigger circuit 140 is adapted to receive a +20 volt DCpower supply potential. This power supply potential along with a and 30volt DC supply potential is provided by AC line 82 being connected tothe primary winding 156 of the power transformer 124. Half waverectifier devices and filter capacitors are coupled to the secondarywinding 158 of transformer 124 in a well known manner to provide therequired DC supply potentials.

Either of the monitor circuits, i.e. the metering unit 22 or the module24, is adapted to sense an abnormal operating condition of the highvoltage signal appearing at output terminal 26 as applied from theprimary fencer unit 54 to cause the holding relay 136 to becomedeenergized in the event of a malfunction. In such an instance, an opencircuit occurs between relay contacts 146 and 148 causing deenergizationof the solenoid 104. Relay contacts and 102 close while contacts 98 and102 open. At the same time, a closed circuit occurs between relaycontacts 126 and 128 supplying AC power now to the back-up fencer 56.

Considering now the circuitry for monitoring the high voltage fenceroutput signal applied to the fence conductor 29, consider first the useof the metering circuit 22. When positioned in the body cavity 18 of thehousing 12 and connected to interface control circuitry 13 throughconnector elements 20 and 52, the transformer 61 whose primary windingis coupled in series between relay terminal 102 and output terminal 26and has its secondary winding coupled to the input of the meteringcircuit by means of leads 64 and 65. In order for the system and moreparticularly the meter unit 22 to operate with all types and makes offencer apparatus wherein either pulse or sinusoidal high voltage signalsare provided, the transformer 61 is selected to exhibit a relativelyhigh impedance across the primary as well as a relatively high (40 kv)breakdown voltage between the primary and secondary. Otherwise the highvoltage will be shorted to ground potential because fencers as is wellknown to those skilled in the art are designed to have very low currentcapability for safety sake. A capacitor 62 is coupled across thesecondary winding for providing a parallel resonant circuit whichgenerates a damped oscillation in the order of ZKHz 10KHz each time ahigh voltage pulse or a sine wave appears across the primary winding.

The metering circuit 22 is adapted to operate such that under normaloperation, a relatively low frequency pulse output signal appears oncircuit lead 66; however, upon sensing an abnormal condition, it isadaptaed to provide a relatively high frequency pulse output signal oncircuit lead 66. A low pass RC filter circuit including resistor 164 andcapacitors 166 and 168 shunt the high frequency pulses to ground whilepassing the low frequency pulses under normal operation to the diodes170 and 172. The diode 172 shunts the positive portion of the pulses toground while diode 170 is poled to allow the negative portions of thepulses to charge capacitor 174 negatively to such a level that FETtransistor 142 is held non-conductive while junction transitor 144 isrendered conductive. This acts to energize the relay coil 138 of holdingrelay 136. in the event of a malfunction, continuous negative pulses areunable to charge capacitor 174 and therefore the accumulated negativecharge thereacross discharges through the series combination of variableresistor 180 and fixed resistor 182 until such time that transistor 142is driven into conduction. This causes transistsor 144 to becomenon-conductive, thereby opening relay contacts 146 and 148. The variableresistor 180 is adapted to provide a predetermined time constant for thedischarge of the capacitor 174 and thus allow the operator to select apredetermined time delay before switching occurs from fencer unit 54 tofencer unit 56.

The second embodiment of the monitor circuit, the module 24 on the otherhand is also adapted to have its input coupled between the high voltageoutput terminal 26 and earth ground terminal 28 by means of circuitleads 67 and 68, male connector elements 53 and 55 and female connectorelements and 21. The circuit is operable such that in normal operatingconditions, a relatively large negative voltage is coupled to circuitjunction 190 to provide sufficient negative voltage across the capacitor174 to maintain transistor 142 non-conductive; however, during anabnormal condition the negative DC output voltage from the circuit 24becomes negative whereupon capacitor 174 discharges to a level wheretransistor 142 becomes conductive while transistor 144 becomesnon-conductive.

Considering now the details of the metering circuit 22 per se, referenceis now made to FIG. 4. As noted above, the metering unit 22 is adaptedfor use not only as a monitor device for the interface controlcircuitry, but also as a portable meter for remote testing of the fence29 as shown in FIG. 2. Accordingly in situ, at +30 volt DC power supplypotential is coupled from the interface controller circuitry via circuitlead 63. This coupling may be made. as noted above, through theconnector members 52 and 20 and connects to +30 volt supply buss 194.

For portable use, however, a 30 volt battery supply 196 is adapted to becoupled to a +30 volt supply buss 194 through a manually operated switch198 and a blocking diode 200. The diode 200 is poled to prevent damageto the battery supply 194 in the event that switch 198 is accidentallyclosed while the metering unit 22 is coupled to the interface controlcircuitry 13. Also the high voltage probe is attached to connector 52 bymeans offemale connector 20'. A high voltage transformer 201 havingcharacteristics substantially the same as transformer. 61 is located inbody 50 of the probe. its primary winding has one end connected to themetal tip 51 while the other end is left floating i. e. not connected toanything. As is the case of transformer 61 the secondary winding oftransformer 201 is parallely resonant with capacitor 204 such thatrelativcly low voltage damped oscillations in the frequency range ofZKHz-lOKHz are produced in response to the tip 51 sensing high voltagesignals on the conductor 29 or disconnects 60 when brought in contacttherewith. As noted for quick checks actual contact with the conductor29 becomes unnecessary since the tip 51 acts as an antenna pick up forthe meter. The transformers 61 and 201 isolate the high voltage to bemonitored or tested from the subsequent meter circuitry 22 shown in FIG.4.

Referring now more particularly to FIG. 4, the potentiometer 206 actsasa manual gain control, the movable element of which is connected bymeans of a relatively high valued fixed resistor 208 to the input of atwo stage DC amplifier comprised of FET transistor 210 and junctiontransistor 212. The output of the second stage transistor 212 iscapacitively coupled to an emitter follower stage comprised oftransistor 214 by means of coupling capacitor 216 The combination oftransistors 210, 212 and 214 provide a high gain low frequency broadbandamplifier having a high input impedance and low output impedance. Thecapacitors 217 and 218 respectively coupled from the input and output ofthe DC amplifier stages provide a high frequency by-pass to groundpotential.

The amplitude of the voltage at the slider contact of potentiometer 206together with gain provided by transistors 210 and 212 effectivelycauses the output of transistor 214 as sensed across the emitterresistor 220 to vary in width. inasmuch as the signal appearing acrossthe secondary winding of either input transformers 61 or 201 is a dampedoscillation an input signal selectively varying in width is applied tothe meter circuit 22. Thus the front end of the meter circuit serves adual purpose, i.e. to amplify weak or low signals and to increase thesignal width. When a pulse type fencer is utilized a meter input signalwill be received for each fencer pulse; however, for a fencer output ofa sine wave type signal for a briefinterval a meter input signal will beforthcoming each time the sinusoidal signal passes through zeropotential.

The signal amplified and appearing across the emitter load resistor 220is capacitively coupled to a pair of diode rectifiers 222 and 224 bymeans of a capacitor 225. The diode 222 clips the positive portion ofthe pulses by shunting them to ground while diode 224 conducts thenegative portions of the pulses to one of three selectable filtercapacitors 226, 228 or 230 which is adapted to charge negatively.Filtering of the signal is necessary to provide a substantially steadynonpulsating DC voltage at junction 234. Capacitor selection is providedby a manually operated selector switch 232. The selection of thecapacitor is dependent upon the repetition rate of the fencer highvoltage signal intervals. The negative DC voltage level appearing acrossthe selected capacitor at circuit junction 234 is therefore dependentupon the value of the capacitor for example capacitor 226 and the valueof the resistor 236. The negative DC voltage level appearing at junction234 is applied to FET transistor 238 which acts simply as a DCamplifier. A DC meter 242 and a series connected calibrating variableresistance 244 is coupled from the output'circuit junction 2400f FETtransistor 238 to ground, providing an indication of the signal levelbeing monitored. The output circuit junction 240 is also connected to avoltage controlled oscillator (VCO) 241 by means of circuit lead 246.

The voltage controlled oscillator 241 comprises a free runningmultivibrator including cross-coupled transistors 248 and 250. Thecircuit lead 246 is connected to the junction of resistors 252 and 254which are respectively coupled to the base of transistors 248 and 250.To initiate operation of the multivibrator, the base of transistor 250is momentarily grounded through the parallel combination of resistor 256and capacitor 258 by closure of a push-button switch 260. The operatingfrequency of the multivibrator is dependent upon the voltage appearingat the output circuit junction 240 of the DC amplifier transistor 238.Accordingly, if the voltage at the drain of transistor 238 decreases,the VCO frequency will increase, while on the other hand if the voltageincreases, the frequency will decrease. The operating frequency of theVCO 241 however is designed to be in the audio range such that an audiotransducer 262 being coupled between the emitters of transistors 248 and250 provides an output tone which can be indicative of system operation.A square wave output signal typical of a multivibrator is taken from thecollector of transistor 250 across resistor 264 and capacitor 266 and iscoupled to interface control circuitry 13 through connector elements 52and on lead 66. The capacitor 266 is adapted to operate in conjunctionwith resistor 164 and capacitors 168 and 166 shown in FIG. 3 to providethe low pass filter circuit referred to above.

Thus in operation if during a monitoring operation the high voltage ACsignal applied to the fence circuit 29 from terminal 26 decreases by apredetermined amount for a predetermined length of time, the negative DCpotential at circuit junction 234 will also decrease, causing the FETtransistor 238 to increase in conductivity. This causes a decrease inthe DC potential at the output circuit junction 240 which causes theoperating frequency of the multivibrator to increase. As mentioned abovewith respect to FIG. 3, the low pass filter circuit will shunt thefrequency signal to ground causing the DC voltage across capacitor 174to become less negative and after a predetermined time delay will causeFET transistor 142 to become conductive while causing transistor 144 tobecome nonconductive. The holding relay 136 accordingly becomesdeenergized and the relay contact terminals 146 and 148 will open,causing the high voltage relay 96 to become deenergized and switch theauxiliary fencer unit 56 into operation and couple its respective highvoltage output to the fence.

When the metering unit 22 is to be used as a portable device for troubleshooting and/or other operations, the gain control potentiometer 206 andselector switch 232 can be used to advantage to change the sensitivityof the meter 242 for responding more readily to the trouble beingsought. Since variation of both the voltage pickoff from thepotentiometer 206 and the negative DC voltage level at circuit junction234 will affect the control voltage of the frequency of the multivibrator. the audio response tone and frequency output from the speakerchanges.

A typical meter calibration and setup procedure for portable use wouldbe as follows: First the fence conductor 29 would be disconnected fromthe interfacecontrol circuitry 13. The female connector 20' of the highvoltage probe would be connected to the male connector element 52 andthe switch 198 would be closed providing battery power to the circuitryshown in FIG. 4.. The push-button switch 260 would be depressed. causingthe VCO 241 comprised of transistors 248 and 250 to become operative.The system would be turned on and by manually moving switch 40 of theinterface controller 13 to position 1, the high voltage fencer unit 54would be energized. Fencer output high voltage now appears at terminals26. The tip 51 of the high voltage probe is placed indirect contact withterminal 26, whereupon the gain potentiometer 206 is ad- 5 justed for asubstantially steady reading from the meter 242 and a constant tone fromthe transducer 262. Subsequent adjustment of the calibration resistor244 will establish a calibration point for the meter 242. Reconnectingthe fence conductor 29 back to terminal 26. the unit 22 with thehigltvoltage probe attached can be moved along the fence noting anyvariation from the calibrated setting previously made.

A very important feature of the meter 22 when used in the portable modeof operation is that it does not re quire a ground return wire to beconnected to earth ground while metering. Also it is adapted to operateat low voltage levels and when desirable at a predetermined distancefrom the fence conductor wire. Thus all dangerous high voltage isconfined to the fence and cannot come in contact with the operator.

While the system may be operated in a manual switching mode with themetering unit 22 removed, automatic switchover is preferable.Accordingly, the plug-in module 24 is substituted for the metering unit22 by coupling it to the female receptacles 20 and 21 in the housing 12by means of the male connector ele ments 53 and 55. The circuit includedin the plug-in module 24 comprises the elements show schematically inFIG. 5 and includes a relatively high resistance voltage divider circuit288 which has circuit leads 67 and 68 adapted to be coupled across thehigh voltage AC output signal terminal 26 ofthe interface controllercircuitry l3 and earth ground. The total resistance value of the voltagedivider must be high enough so as not to affect the fencer output whichas noted before is adapted to drop if a low resistance is appliedbetween conductor 29 and earth ground 15. A light sensitive impedanceelement 290 has one end connected to the 30 volt DC supply potential bycircuit lead 69, while the other side is suitably coupled to circuitlead 70. Both of these circuit leads couple to interface controlcircuitry through connector elements 53 and 20. The impedance element290 is enclosed in a light tight housing or enclosure 292 along with alight emitting device 294 which is energized by connection to apredetermined voltage tap 295 of the voltage divider 288. Thus when fullhigh voltage appears on terminals 26, sufficient voltage is present tocause the light emitting device 294 to operate. The device 294 transmitsits light output to the impedance 290 which decreases in value,lessening the voltage drop thereacross such that the cireuitjunction(FIG. 3) is sufficiently negative to maintain transistor 142non-conductive and transis tor 144 conductive. In the event that thehigh voltage output decreases to an abnormal value, the light energyemitted by the device 294 lowers, causing the impedance value of thelight sensitive impedance 290 to increase, causing the voltage appliedto circuit junction 190 to be less negative. As before, the transistor142 will become conductive, which in turn causes transistor 144 tobecome non-conductive. The holding relay 136 deenergizes causing thesystem to switch from fencer unit 54 to the back-up fencer unit 56.

While the circuitry in FIG. 5 is disclosed for purposes of explanationas a circuit which is coupled into the system as a monitoring circuit inplace of the metering unit 22, it should be pointed out that whendesirable. the

same circuitry could be permanently made part of the interface controlcircuitry 13 such that it would be automatically connected to circuitjunction 190 when the metering unit 22 is removed from the body cavityof the housing 12 and then automatically disconnected when the meteringunit 22 is again reconnected to the interface control circuitry. Also,when desirable, the circuitry 24 shown in FIG. could be the solemonitoring circuit utilized in combination with the circuitry 13obviating the need for any direct connection of the metering unit 22 tothe circuit shown in FIG. 7, it being then used completely for remoteportable use for testing the fence circuit and other select functions.

Completing the disclosure, the fence conductor 29 shown in FIG. 2 alsocouples one or more fence disconnect means 60 which is essentially ameans for interrupting the high voltage fence conductor at a selectedlocation along the fence perimeter. Each disconnect means 60 is mountedon a respective wire supporting pole in place of the regular poleinsulator. The disconnect means itself is relatively simple inconstruction,

' having a housing 270 secured to a bracket 272 which is mountable onthe support pole. Projecting from the housing wall are a pair of opposedconnector means 274 and 276 for attachment to the fence circuitconductor. lnteriorally of the housing is a dielectric disc type element278 having a conductor element 279 runningtherethrough or partiallytherearound. The dielectric element is attached to a spring loadedspindle 280 coupled to an external knob member 282 which is adapted formanual rotation. Rotation of the knob 282 turns the dielectric element278 to a position wherein the electrical conductor 279 makes electricalcontact with both connectors 274 and 276. With the electrical fenceconductor permanently connected to the connector elements 274 and 276 asimple quarter turn of the knob 282 will for example break theelectrical circuit, while a subsequent rotation back to the initialposition will reestablish circuit continuity. By moving from onedisconnect means 60 to another along the fence circuit 29, the absenceof fence high voltage or shorts can be found very easily and quickly,utilizing the portable metering unit 22 previously described. Fencedisconnect switches 60 positioned at predetermined intervals along thefence circuit 29 becomes very important, particularly where theelectrified fence is relatively long.

While the present invention has been shown and described with what is atpresent considered to be the preferred embodiment of the subjectinvention, it should be pointed out that the present specification isnot meant to be interpreted in a limiting sense, but it is to beconsidered by way of example only. Accordingly, other modifications andchanges becoming obvious in view of the present disclosure is hereinmeant to be intended without departing from the spirit and scope of theinvention as set forth in the following claims. Accordingly,

We claim as our invention:

1. An automatic monitoring and switching system including energizingmeans for transferring an electrified fence from a first fencer unit toa second fencer unit, comprisingin combination:

first circuit means including circuit transfer means coupled to andadapted to selectively receive a high voltage signal from each of saidfencer units when respectively energized from said energizing means,said circuit transfer means having a first and second operating stateand in said first operating state being operable to apply said highvoltage signal from said first fencer unit;

switch means having a first and second operating state and in its firstoperating state initially energizing said first fencer unit and causingsaid circuit transfer means to assume its respective first operatingstate and couple said high voltage signal from said first fencer unit tosaid fence;

monitor circuit means coupled to and adapted to be responsive to thehigh voltage signal applied to the fence and being operable to provide afirst type control signal during a predetermined normal operating stateof the system and a second type control signal during a predeterinedabnormal operating state of the system; and

second circuit means coupled to and being responsive to said controlsignals from said monitor circuit means and including circuitinterruptor means coupled to said circuit transfer means, said circuitinterruptor means being operable in response to said'first type controlsignal from said monitor circuit means to maintain said circuit transfermeans operable in said first operating state and said first fencer unitenergized when said switch means is in its respective second operatingstate, said circuit interruptor means being further operable in responseto said second type control signal to cause said circuit transfer meansto assume its respective second operating state when said switch meansis in its second operating state thereby energizing and coupling saidsecond fencer unit to the fence while deenergizing and uncoupling saidfirst fencer unit therefrom.

2. The system as defined by claim 1 wherein said circuit transfer meansand said circuit interruptor means respectively comprise a first andsecond electrically operated relay, and

wherein said switch means comprises a manually operated system resetswitch having first and second positions for providing said first andsecond operating states.

3. The system as defined by claim 2 wherein said first and second typecontrol signals from said monitor circuit means comprises first andsecond voltage amplitude signals, and

wherein said second circuit means comprises voltage amplitude responsivecircuit means coupled to said second relay for energizing said relay inresponse to said first amplitude voltage signal and deenergizing saidrelay during said second voltage amplitude signal.

4. The system as defined by claim 3 wherein said voltage amplituderesponsive circuit means comprises a Schmitt trigger circuit.

5. The system as defined by claim 3 wherein said first and secondvoltage amplitude signals comprise DC signals, and wherein said secondcircuit means includes a charging capacitor having a selectableresistive discharge path, said capacitor being adapted to be charged bysaid first DC signal.

6. The system as defined by claim 5 and wherein said monitor circuitmeans comprises:

a voltage divider network coupled across said high voltage signalapplied to said fence;

a source of direct current voltage and a variable impedance elementcoupled between said DC source and said capacitor; and

means coupled to said voltage divider network and being responsive to aportion of the voltage thereacross for varying the impedance of saidvariable impedance element.

7. The monitor circuit means as defined by claim 6 wherein said lastrecited means comprises a light emitting device, the intensity of whichis a function of said voltage portion, coupled to an intermediatevoltage tap of said voltage divider network and wherein said variableimpedance element comprises a light sensitive device optically coupledto said light emitting device and being adapted to vary its impedance inaccordance with the intensity ofthe light generated by said lightemitting device.

8. The system as defined by claim and additionally including firsttransformer means coupled to said high voltage signal and providing anoscillatory signal therefrom and wherein said monitor circuit meanscomprises:

input circuit means disconnectably coupled to said first transformermeans and being responsive to said oscillatory signal provided thereby;

circuit means developing a DC voltage, the ampli tude of which is afunction of the oscillatory signal coupled to said input circuit means;and voltage controlled oscillator coupled to said last recited circuitmeans generating an AC output signal whose frequency varies according tothe DC voltage developed by said last recited circuit means, said outputsignal being coupled to said second circuit means; and

wherein said second circuit means additionally includes frequency filtercircuit means adapted to pass selected output signal frequencies fromsaid voltage controlled oscillator, and rectifier means coupled betweensaid filter means and said charging capacitor for providing a DC voltageof a pre determined polarity from said output signal frequencies passedby said filter circuit means to control said amplitude responsivecircuit means.

9. The monitor circuit means as defined by clalim 8 and additionallyincluding a voltage meter and calibrating means therefor coupled acrosssaid circuit means developing said DC voltage for providing anindication of the amplitude level of said high voltage signal coupled tosaid input means.

10. The monitor circuit means as defined by claim 9 wherein said monitorcircuit means when disconnected from said first transformer means isutilized as a portable metering unit, and additionally including a highvoltage probe connected to said monitor circuit means and coupled tosaid input circuit means, said probe including an insulated housing,second transformer means located in said housing and coupled to saidinput means and being adapted to provide an oscillatory signal inresponse to said high voltage signal, and a conductive probe tipattached to said housing and electrically coupled to said secondtransformer means, said tip being adapted to sense said high voltagesignal and shock excite said second transformer means to generate saidoscillatory signal.

11. The monitor circuit means as defined by claim 10 wherein said inputcircuit means additionally includes variable gain signal amplifier meanscoupled between said second transformer means and a rectifier means, andDC amplifier means coupled between said rectifier means and said voltagecontrolled oscillator.

12. The monitor circuit means as defined by claim 11 and additionallyincluding at least one charging capacitor and a discharge path thereforof predeterined time constant coupled to said rectifier means, saidcapacitor being charged therefrom and the voltage appearing thereacrossbeing applied to said DC amplifier means.

13. The monitor circuit means as defined by claim 12 wherein saidvariable gain amplifier means comprises transistor amplifier meansincluding an emitter follower output circuit coupled to said rectifiermeans and potentiometer means coupling said second transformer means tothe input of said transistor amplifier means.

14. The monitor circuit means as defined by claim 8 wherein said voltagecontrolled oscillator comprises a voltage controlled free runningmultivibrator.

15. The monitor circuit means as defined by claim 14 and additionallyincluding an audio transducer coupled across said multivibratorproviding an audio indication of the output frequency of saidmultivibrator.

l 4'= f l =i

1. An automatic monitoring and switching system including energizingmeans for transferring an electrified fence from a first fencer unit toa second fencer unit, comprising in combination: first circuit meansincluding circuit transfer means coupled to and adapted to selectivelyreceive a high voltage signal from each of said fencer units whenrEspectively energized from said energizing means, said circuit transfermeans having a first and second operating state and in said firstoperating state being operable to apply said high voltage signal fromsaid first fencer unit; switch means having a first and second operatingstate and in its first operating state initially energizing said firstfencer unit and causing said circuit transfer means to assume itsrespective first operating state and couple said high voltage signalfrom said first fencer unit to said fence; monitor circuit means coupledto and adapted to be responsive to the high voltage signal applied tothe fence and being operable to provide a first type control signalduring a predetermined normal operating state of the system and a secondtype control signal during a predeterined abnormal operating state ofthe system; and second circuit means coupled to and being responsive tosaid control signals from said monitor circuit means and includingcircuit interruptor means coupled to said circuit transfer means, saidcircuit interruptor means being operable in response to said first typecontrol signal from said monitor circuit means to maintain said circuittransfer means operable in said first operating state and said firstfencer unit energized when said switch means is in its respective secondoperating state, said circuit interruptor means being further operablein response to said second type control signal to cause said circuittransfer means to assume its respective second operating state when saidswitch means is in its second operating state thereby energizing andcoupling said second fencer unit to the fence while deenergizing anduncoupling said first fencer unit therefrom.
 2. The system as defined byclaim 1 wherein said circuit transfer means and said circuit interruptormeans respectively comprise a first and second electrically operatedrelay, and wherein said switch means comprises a manually operatedsystem reset switch having first and second positions for providing saidfirst and second operating states.
 3. The system as defined by claim 2wherein said first and second type control signals from said monitorcircuit means comprises first and second voltage amplitude signals, andwherein said second circuit means comprises voltage amplitude responsivecircuit means coupled to said second relay for energizing said relay inresponse to said first amplitude voltage signal and deenergizing saidrelay during said second voltage amplitude signal.
 4. The system asdefined by claim 3 wherein said voltage amplitude responsive circuitmeans comprises a Schmitt trigger circuit.
 5. The system as defined byclaim 3 wherein said first and second voltage amplitude signals compriseDC signals, and wherein said second circuit means includes a chargingcapacitor having a selectable resistive discharge path, said capacitorbeing adapted to be charged by said first DC signal.
 6. The system asdefined by claim 5 and wherein said monitor circuit means comprises: avoltage divider network coupled across said high voltage signal appliedto said fence; a source of direct current voltage and a variableimpedance element coupled between said DC source and said capacitor; andmeans coupled to said voltage divider network and being responsive to aportion of the voltage thereacross for varying the impedance of saidvariable impedance element.
 7. The monitor circuit means as defined byclaim 6 wherein said last recited means comprises a light emittingdevice, the intensity of which is a function of said voltage portion,coupled to an intermediate voltage tap of said voltage divider networkand wherein said variable impedance element comprises a light sensitivedevice optically coupled to said light emitting device and being adaptedto vary its impedance in accordance with the intensity of the lightgenerated by said light emitting device.
 8. The system as defined byclaim 5 and additionally including first tRansformer means coupled tosaid high voltage signal and providing an oscillatory signal therefromand wherein said monitor circuit means comprises: input circuit meansdisconnectably coupled to said first transformer means and beingresponsive to said oscillatory signal provided thereby; circuit meansdeveloping a DC voltage, the amplitude of which is a function of theoscillatory signal coupled to said input circuit means; and a voltagecontrolled oscillator coupled to said last recited circuit meansgenerating an AC output signal whose frequency varies according to theDC voltage developed by said last recited circuit means, said outputsignal being coupled to said second circuit means; and wherein saidsecond circuit means additionally includes frequency filter circuitmeans adapted to pass selected output signal frequencies from saidvoltage controlled oscillator, and rectifier means coupled between saidfilter means and said charging capacitor for providing a DC voltage of apredetermined polarity from said output signal frequencies passed bysaid filter circuit means to control said amplitude responsive circuitmeans.
 9. The monitor circuit means as defined by clalim 8 andadditionally including a voltage meter and calibrating means thereforcoupled across said circuit means developing said DC voltage forproviding an indication of the amplitude level of said high voltagesignal coupled to said input means.
 10. The monitor circuit means asdefined by claim 9 wherein said monitor circuit means when disconnectedfrom said first transformer means is utilized as a portable meteringunit, and additionally including a high voltage probe connected to saidmonitor circuit means and coupled to said input circuit means, saidprobe including an insulated housing, second transformer means locatedin said housing and coupled to said input means and being adapted toprovide an oscillatory signal in response to said high voltage signal,and a conductive probe tip attached to said housing and electricallycoupled to said second transformer means, said tip being adapted tosense said high voltage signal and shock excite said second transformermeans to generate said oscillatory signal.
 11. The monitor circuit meansas defined by claim 10 wherein said input circuit means additionallyincludes variable gain signal amplifier means coupled between saidsecond transformer means and a rectifier means, and DC amplifier meanscoupled between said rectifier means and said voltage controlledoscillator.
 12. The monitor circuit means as defined by claim 11 andadditionally including at least one charging capacitor and a dischargepath therefor of predeterined time constant coupled to said rectifiermeans, said capacitor being charged therefrom and the voltage appearingthereacross being applied to said DC amplifier means.
 13. The monitorcircuit means as defined by claim 12 wherein said variable gainamplifier means comprises transistor amplifier means including anemitter follower output circuit coupled to said rectifier means andpotentiometer means coupling said second transformer means to the inputof said transistor amplifier means.
 14. The monitor circuit means asdefined by claim 8 wherein said voltage controlled oscillator comprisesa voltage controlled free running multivibrator.
 15. The monitor circuitmeans as defined by claim 14 and additionally including an audiotransducer coupled across said multivibrator providing an audioindication of the output frequency of said multivibrator.